S eismic wave P ropagation and I maging in C omplex media: a E uropean network

1. Seismic wave Propagation and Imaging in Complex media: a European network Shane Murphy Early Stage Researcher Host Institution: University of Naples Place of Origin: Dublin, Ireland Appointment Time: January 2005 Project: Earthquake scaling with initial rupture phase Task Groups: TG Local Scale, TG Small Scale Cooperation: INGV Rome

2. Introduction Scaling of frequency with magnitude size After: Olsen & Allen (2005)

3. Introduction Scaling of peak motion with magnitude size From Zollo , Lancieri & Nielsen (submitted)

4. Theory Looking at the far displacement for a double couple point source…… u(t) Λ u ∆σΛ

5. Theory Looking at shear fracture exclusively…… Energy Flow:  y o r 

6. Theory In the case of the Antiplane Stress Intensity Factor Steady state pulse Kostrov crack Self-similar pulse The Stress Intensity, K, always depends on the Sqrt(Λ) & ∆σ

7. Theory Combining the two equations …… Energy Flow: ∆σΛ u  Ge

8. Graphical Depiction of Model σ y Triggering patch σ a σ Asperity b background R1 R2 L

9. The model Triggering patch High-stress asperity Fault plane Background stress Final rupture size?

10. The model High-stress asperity Fault plane Background stress Final rupture size? Mo ini Mo

11. The model

12. The model sliprate 0 2.74 Model Parameters: Trigger Radius: 10 Asperity Radius: 20 Yield Stress: 1.2 Asperity Stress: 0.8 Background Stress: 0.6

13. Results Rupture Length Versus Moment Rate Moment Rate

14. Results Moment Rate (Far Field Displacement) Peak Mo.rate (R2) Moment rate (far field displacement) Start healing Fracture stops Time

15. Results Scaling of Magnitude with Moment Rate

16. Problem – Slip Distribution Slip Pattern Unphysical as nucleation usually found outside zone of major slip 2.08 3.02 slip slip 0 0 y y

17. Future Work Different model types Moving Nucleation Location Heterogeneous Stress Distribution Rupture Time History Synthetic Seismograms P - arrival

18. Thank you The End